<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        html,body{
            height: 100%;
            width: 100%;
        }
         body{
            background-color: pink;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
        }
        .p1{
            width: 200px;
            height: 200px;
            background-color: red;
            position: relative;
            transform:rotate(45deg);
            animation: yqx 2s alternate infinite;
            box-shadow: 0 0 30px red;
        }
        .p1::before{
            content: "";
            width: 200px;
            height: 100px;
            background-color: red;
            position: absolute;
            left: 0;
            top: -99px;
            border-radius: 100px 100px 0 0;
            box-shadow: 0 0 30px red;
        }
        .p1::after{
            content: "";
            width: 100px;
            height: 200px;
            background-color: red;
            position: absolute;
            top: 0;
            left: -99px;
            border-radius: 100px 0 0 100px;
            box-shadow: 0 0 30px red;
        }
        @keyframes yqx {
            0%{
                transform: rotate(45deg) scale(0.8);
            }
            100%{
                transform: rotate(45deg) scale(1.4);
            }
        }
    </style>
</head>
<body>
    <div class="p1"></div>
</body>
</html>